The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
To produce resistant and lightweight structural elements, particularly in the aeronautical field, it is known to prepare a textile preform from dry fibers, in particular carbon fibers, by draping parts such as fabrics, fiber ribbons or braids, which are successively deposited on a molding shape to form superposed layers.
The layers of the preform may be bonded together by various means, in particular by a consolidation resin, a heat fusible agent such as a thermoplastic organic compound, or a seam.
The preform is then impregnated with a resin, in particular by injection according to a liquid composite molding method called “LCM,” or resin transfer molding called “RTM.” Alternatively, it is possible to produce such a preform with parts made of fibers pre-impregnated with resin.
After baking the resin, a lightweight part is obtained which may have various shapes, comprising fibers whose density and orientation are adjusted depending on local constraints, in order to obtain high mechanical strength characteristics.
In the aeronautical field, such parts are produced to form turbojet engine nacelle elements, in particular continuous-fiber monolithic composite parts, such as thrust reverser structure frames, or acoustic or non-acoustic sandwich composite panels such as acoustic cowls of thrust reversers, air intake lips or cowls.
To produce a part with a non-developable shape, a known production method consists in draping on a molding shape, having a corresponding non-developable surface, fiber fabrics which are deformed to adapt to this molding shape by avoiding wrinkles. This method is expensive and delicate, in particular for producing uneven or complex geometric shapes.
Another known method for manufacturing a part of revolution comprising a final shape that cannot be developed, presented in particular by document WO-A2-2014044963, consists in designing a mandrel giving a predefined initial shape compared to the final shape of the part of revolution, weaving fibers together in weft and warp, wrapped on this mandrel, and finally applying a transformation of this woven preform to obtain the final shape corresponding to the part to be obtained.
This method is adapted only to the shapes of revolution and is limited, in regards to the fiber orientations on the final part, by the limitations that the weaving offers.
Moreover, the draping methods by automated depositing of fibers or layers of fibers using draping heads allow reducing draping costs, and arranging the fibers or layers of fibers in all orientations on non-developable shapes, which can be of revolution or not, in order to optimize the mass and improve the manufacturing costs.
However, with these methods, it is not possible to produce some particular shapes of the preform with the automated draping machines, such as in particular small radii or two closed angles between two portions, because of the bulk of the fiber depositing rollers whose dimensions do not allow accessing and applying fibers on surfaces in confined spaces.